This invention relates generally to coating of substrates with an antiskid material and more particularly concerns the coating of substrates with an antiskid material in the form of a silica aquasol, provision being made for observing the uniformity of the coating applied to the substrate.
It is quite common in coating applications to coat a substrate several times, often with a coating which is hard to see with human eye. While this is a common problem with a clear coating, it is also a problem when coatings of similar color to the substrate are made. Often in these coating operations the applicator becomes blocked causing a non-uniform coating to be applied and it is necessary to quickly discover that the application is not uniform so as to correct the applicator.
Some attempts to discover this have used an indicator spray which is sprayed on the coating and gives a characteristic color if the silica is present. However, these indicators have been confined to use on special test panels of the coated substrate which are run infrequently, usually at the start up of the coating application and at spaced intervals to recheck. These indicator sprays cannot be applied to a wet coating due to the solvent incompatability, so the coated substrate must be at least partially dried before the indicator spray is usable. These indicator sprays also form a permanent color change which renders any sprayed coated substrate unusable, so the test panels are usually discarded.
Accordingly it is an object of this invention to provide a composition and method for easily observing the uniformity of application of a silica sol coating. Another object is to provide a means for observing the uniformity of an aqueous silica sol coating application while the coating is still wet. An allied object is to provide a composition and method for observing the uniformity of a silica coating on a substrate without rendering the substrate unusable. A related object is to develop a composition which meets the above objects and one which does not have any adverse effects on the antiskid coating.